The present invention comprises a new and distinct cultivar of apple tree botanically classified as Malus domestica (Borkh.) and known by the varietal name ‘UEB 42721’.
The new variety is the result of a cross in a planned breeding program between ‘Evereste’ (female parent, unpatented) and ‘Maypole’ (male parent, U.S. Plant Pat. No. 6,184). The cross resulting in ‘UEB 42721’ occurred in the Spring of 2003 at 310 meters above sea level with a mean annual temperature of 7.7° C. and a mean annual precipitation of 680 mm. The purpose of the breeding program was to develop an ornamental apple variety having a unique appearance with a columnar tree growth type that exhibits Vf-resistance against scab. The new variety was discovered in 2009 with the first flowering and fruiting of the original seedling in the Czech Republic. Subsequently, the new variety was asexually reproduced in Pencin u Liberce in the Czech Republic by budding/grafting on apple rootstocks in the Spring of 2014.
The new variety is similar to its female parent, ‘Evereste’, in exhibiting small fruits with no russeting present and Vf-resistance against scab. However, ‘UEB 42721’ exhibits a columnar tree growth type, red-purple flower petals, and red to red-purple fruit skin color, while ‘Evereste’ exhibits a ramified tree growth type, white flower petals, and yellow fruit skin color with an orange to red blush present. The new variety is similar to its male parent, ‘Maypole’, in exhibiting a columnar tree growth type, red-purple flower petals, and long fruit stalk. However, ‘UEB 42721’ differs from ‘Maypole’ in exhibiting fruits that persist longer, are smaller in size, and are broadly globose in shape versus round-conical in shape.
Further, when compared to apple tree named ‘UEB 42723’ (U.S. Plant patent application Ser. No. 15/932,513, concurrently applied-for herewith), both varieties exhibit a columnar tree growth type and Vf-resistance against scab. However, ‘UEB 42721’ exhibits an erect growth habit and a broadly globose fruit shape, while ‘UEB 42723’ exhibits a compact growth habit and an ovoid fruit shape.
The following characteristics also distinguish the new variety from other varieties known to the breeders:                Late ripening, ornamental, diploid variety;        Columnar tree growth type;        Very narrow, erect, and compact growth habit with short internodes;        Weak to medium tree vigor;        Red-purple color of unopened and open flowers;        Medium time to beginning of flowering;        Greyed-purple color of young leaves and green tinted color of mature leaves;        Fruit is small in size and broadly globose in shape;        Very long time of fruit persistence; and        Resistance against scab on Vf-gene basis.        
The new variety has been trial and field tested and has been found to retain its distinctive characteristics and remain true to type through successive asexual propagations.